Kinetic Resolution of Allyltriflamides through a Pd-Catalyzed C-H Functionalization with Allenes: Asymmetric Assembly of Tetrahydropyridines.

Enantioenriched, six-membered azacycles are essential structural motifs in many products of pharmaceutical or agrochemical interest. Here we report a simple and practical method for enantioselective assembly of tetrahydropyridines, which is paired to a kinetic resolution of α-branched allyltriflamides. The reaction consists of a formal (4+2) cycloaddition between the allylamine derivatives and allenes and is initiated by a palladium(II)-catalyzed C-H activation process. Both the chiral allylamide precursors and the tetrahydropyridine adducts were successfully obtained in high yields, with excellent enantioselectivity (up to 99% ee) and selectivity values of up to 127.

Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow.

The first example of photocatalytic trifluoromethoxylation of arenes and heteroarenes under continuous-flow conditions is described. Application of continuous-flow microreactor technology allowed to reduce the residence time up to 16 times in comparison to the batch procedure, while achieving similar or higher yields. In addition, the use of inorganic bases was demonstrated to increase the reaction yield under batch conditions.

Rhodium(III)-Catalyzed Annulation of 2-Alkenyl Anilides with Alkynes through C-H Activation: Direct Access to 2-Substituted Indolines.

A RhIII complex featuring an electron-deficient η5 -cyclopentadienyl ligand catalyzed an unusual annulation between alkynes and 2-alkenyl anilides to form synthetically appealing 2-substituted indolines. Formally, the process can be viewed as an allylic amination with concomitant hydrocarbonation of the alkyne. Mechanistic experiments indicate that this transformation involves an unusual rhodium migration with a concomitant 1,5-H shift.

Palladium-Catalyzed Formal (5 + 2) Annulation between ortho-Alkenylanilides and Allenes.

2-Alkenyltriflylanilides react with allenes upon treatment with catalytic amounts of Pd(OAc)2 and Cu(II) to give highly valuable 2,3-dihydro-1H-benzo[b]azepines, in good yields, and with very high regio- and diastereoselectivities. Density functional theory (DFT) calculations suggest that the C-H activation of the alkenylanilide involves a classical concerted metalation-deprotonation (CMD) mechanism.